Prevalence of Rediae and Cercariae of Thiarid Snails in Piao River, Municipality of Pres. Manuel A. Roxas, Zamboanga del Norte

Abstract

The Thiaridae family, which serves as the first intermediate host of Paragonimus westermani, was investigated for the prevalence rate of cercarial and redial infection. On October 2009, snails were collected from Piao River in Municipality of Pres. Manuel A. Roxas, Zamboanga del Norte, an area endemic for paragonimiasis. A total of 955 thiarid snails, which consisted of Melanoides granifera (81.78%), M. maculata (6.49%), Thiara sp. (A) (4.71%) and Thiara sp. (B) (7.02%), were collected from three sites (Brgy. Piao, Brgy. Pinalan, Brgy. Marupay) all of which were examined for infection using crushing method. No snails were found to be infected with P. westermani. However, pleurolophocercous or parapleurolophocercous cercariae were found to infect M. granifera while Philophthalmus sp. cercaria was found to infect M. maculata. The river is an important source of infection for all sites for parasites harbored by Thiara sp. and M. granifera like P. westermani and heterophyid cercariae because of uniform snail density for these species. Brgy. Marupay was found to have high potential for transmission for Philophthalmus sp. because M. maculata was found to be significantly abundant in this area (p>0.05).Presence of the flukes warrants informing the residents of possible transmission.